One of the world's biggest sperm banks has warned that Danish government plans to tax its donors could shut it down.

Cryos International Sperm Bank, based in the Danish town of Aarhus, protested after being asked to reveal details of men who sell their sperm to the bank.

It says only 7% of donors would carry on if they were liable for tax on the 500 kroner ($85; £47) they get paid.

Cryos says it receives 30 to 60 sperm donations a day at its three branches, mostly from students.

The bank makes 10m kroner ($1.7m; £950,000) a year from sales, which contribute to about 1,000 pregnancies annually.

Donating sperm to Cryos has been tax-exempt since 1990, but financial authorities are seeking to overturn this by requiring the bank to disclose who the donors are and how much money they make.

In a letter to Taxation Minister Kristian Jensen, the company defended the donors' right not to pay tax, saying: "It is a special kind of work and the fees paid cannot be compared to normal working income."

It said the number of men selling their sperm anonymously was already in decline, from 250 five years ago to 163 this year.